Brake control means



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Patented Oct. 29, 1935 UNITED STATES PATENT OFFICE BRAKE CONTROL MEANSJohn W. Logan, Jr., Edgewood, Pa., assignor to The Westinghouse AirBrake Company, Wilmerding, Pa., a corporation of Pennsylvania Originalapplication Jan uary 19, 1934, Serial No.

This invention relates to brake control means, and in particular tomeans for releasing the brakes on slipping or sliding wheels of railwayvehicles. This application is a division of my copending application,Serial No. 707,282, filed January 19, 1934, for an Electropneumaticbrake.

It is well known to those skilled in the art that the coeflicient offriction between the rubbing parts of friction brakes commonly employedin y connection with railway vehicles and trains is greater at lowrotational speeds than at high rotational speeds. As a consequence, iffriction brakes are applied with a maximum braking force at high speeds,the braking force must be reduced I as the speed of the vehicle or traindiminishes, or otherwise sliding of the wheels may be caused. Wheelsliding is objectionable in that the retarding force due to slidingwheels is less than that due to rolling wheels, and also because flatplaces are worn on the treads of the wheels when they slide, renderingthem unfit for regular service.

It is also well known that not all of the wheels on a vehicle or trainare caused to slide, but most generally only a few wheels slide. It istherefore highly desirable that means be provided for releasing thebrakes on only those wheels which slide, rather than releasing thebrakes on all of the vehicle or train wheels, and thereby lengtheningthe stop.

It is a principal object of the present invention to provide means forreleasing the brakes on only those wheels which slide or reduce in speedbelow that corresponding to the speed of the vehicle.

Other and more specific objects of the invention will be apparent fromthe following description, which is taken in connection with the singlefigure of the attached drawing which illustrates one form which theinvention may take.

Referring to this drawing, I have shown a simple straight air brakesystem comprising duplex brake cylinders Ill, [2, l4 and I6, and a brakevalve device l8 for controlling the supply of fiuid under pressure toand its release from all of the brake cylinders.

The brake cylinders l0, I2, l4 and I6 are preferably duplicates, eachbrake cylinder containing pistons and 22 adapted to move in oppositedirections when fluid under pressure is supplied to the brake cylinder.When the two pistons 20 and 22 move outwardly, each actuates a shoe 24into engagement with a brake drum 23, through a lever diagrammaticallyshown at 28, and pivoted intermediately its ends at 30. The two shoes 24associated with each drum 26 are normally held out of engagement withthe by the action of springs 32 in each of the brake cylinders. By wayof illustration, 1 have shown four brake drums 26, each of which isassociated with a vehicle axle 33, but any other number may of course beemployed.

While the brake cylinders and mechanism for actuating the brake shoeshave been shown in rather diagrammatic and elementary form, it is to beunderstood that I contemplate using a type of mechanism such as iscommonly employed for fluid pressure apparatus of this type.

For controlling the supply of fluid under pressure to and its releasefrom each of the brake cylinders l0, l2, I4 and I6, respectively,according to whether or not the wheels associated with 15 the brake drumare rolling or sliding, I have provided magnet valve devices 34, 36, 38and 40. Each of these magnet valve devices is embodied in a casingprovided with a supply chamber 4|, a release chamber 42, and anintermediate chamber 0 43. Disposed in the intermediate chamber 43 is adouble beat valve 44. The double beat valve 44 is urged toward a lefthand seated position by a spring 45, and toward a right hand seatedposition by action of an electromagnet in the left end of 26 the casing,which when energized actuates the double beat valve to the right.

When the double beat valve 44 is in the left hand seated position, fluidunder pressure may flow from a supply pipe 46 past the open right handseat to the connected brake cylinder. When the double beat valve isactuated to its right hand seated position, this flow is cut off and thepressure in the brake cylinder is released to the atmosphere, past theopen left hand seat, and through a port 41.

Energization of the four electromagnets in the four magnet valve devicesis controlled, respectively, by four relays 43, 49, 50 and 5|. Each ofthese relays contains an upper coil and a lower coil, as shown in thedrawing. These upper and lower coils are wound oppositely, and the twocoils of each relay are connected in series across output terminals 31of a full-wave rectifier device 52, 45 there being a rectifier devicefor each relay.

The input terminals 39 of each of these rectidevices 52 are connected toa winding 54 associated with a permanentmagnet 56 disposed adjacentlyone of the brake drums 26. Each of 60 the brake drums 26 is providedwith uniformly spaced projections 58 adapted to move past the polepieces of one permanent magnet 56 when the associated brake drum isrotating, so that a magnetic path of periodically varying reluctance isprovided through the brake drum for the flux set up by the permanentmagnet.

As each of the brake drums 26 rotates then, the magnetic flux in eachmagnet 56 is caused to vary, and as a consequence an alternatingelectromotive force is generated in each winding 54. This alternatingelectromotive force is impressed upon the input terminals of theconnected rectifier device 52, and the rectifier device delivers to theoutput terminals a relatively unidirectional current which flows to theconnected relay.

In each of the conductors leading from the lower coil of each of therelays to the associated rectifier device 52, there is disposed avalvular device 60, which is adapted to permit the flow of current onlyin the direction indicated by the arrow head. This device may be of anyof the types commonly employed for this purpose, as for example thecopper oxide rectifier type.

The top coil of each relay is connected by a conductor 6| to therectifier device associated with the adjacent relay, as is indicated inthe drawing, so that all of the top coils form a series circuit whichalso includes all of the rectifier devices 52, as well as a currentlimiting resistance device 52, which however may not be required in allcases. The lower coil of each relay is then in effect shunted across aseries combination including an upper coil and a rectifier device.

The operation of this embodiment of my invention is as follows:

When the vehicle is running, the handle 64 of the brake valve device I8is maintained in release position. In this position each of the brakecylinders Ill, I2, l4 and I6 will be vented to the atmosphere and thebrakes will thus be held released.

When the train is running all of the brake drums 26 will be rotating atsubstantially the same speed, and the electromotive forces generated inthe windings 54 will be substantially equal. The electromotive forceimpressed upon the input terminals of each of the rectifier devices 52will therefore be substantially equal, and the current flowing throughthe series combination of the top coils of the relays will cause each ofthese coils to be energized alike. In a similar manner, the currentflowing through the bottom coils of each of the relays will besubstantially the same. The windings of the top and bottom coils are soproportioned that for this condition the magnetic effects produced bytwo coils neutralize each other and the relays are ineffective to closetheir contacts 65.

To effect an application of the brakes, the brake valve handle 64 isoperated in the usual manner to supply fluid under pressure from asource of supply, as for example a reservoir 66, to the brake cylindersto a degree in accordance with a desired degree of braking.

If now with the brakes thus applied, it be assumed that the wheelsassociated with the extreme left hand axle 33, and brake drum 26, be-vgin to slip and hence decrease in speed below that corresponding to thespeed of the vehicle, the electromotive force generated in the winding54 associated with that brake drum will be diminished, with the resultthat the current supplied to both the top and bottom coils of the relay48 will be diminished.

The current in the bottom coil is however diminished more than thecurrent in the top coil, as the top coil is in the series circuit whichreceives current from all of the windings 54, whereas the bottom coilreceives current only from the one winding 54, due to action of theconnected valvular device Gil. The magnetic force of the top coiltherefore overbalances that of the lower coil and is effective inclosing the contacts 65 of relay 48. Closing of these contacts energizesthe electromagnet in the magnet valve device 34, from battery 63, andits double beat valve 44 will therefore be actuated to its right handseated position. The supply of fluid under pressure to the brakecylinder l0 will thus be cut off, and pressure in the brake cylinderreleased to, the atmosphere. The brakes on the slipping wheels will thusbe released, while the brakes on the other wheels are unafiected.

As soon as suflicient pressure has been released from the brake cylinderIt] so that the slipping wheels begin to rotate again, the electromotiveforce generated in the winding 54 associated with these wheels willagain increase, and the current in the top and bottom coils willagainbalance. The contacts of relay 48 will then open, the electromagnet inthe magnet valve device 34 deenergized, and fluid under pressure mayagain be supplied to the brake cylinder I0. If the wheels should againeither slip or slide, the operation just described will be repeated.

Now the parts may be designed so that the pressure in the brake cylinderor cylinders associated with slipping wheels may be reduced fast enoughto prevent the wheels from reaching a locked wheel stage, and all wheelsthereby kept rolling.

If the wheels associated with more than one of the brake drums shouldslide, it will be obvious that one or more of the relays will close itscontacts, to release the brakes on as many wheels as are slipping orsliding. The apparatus therefore functions to release the brakes on onlythose wheels which slip or slide without affecting the brakes on wheelswhich do not slip or slide.

While I have illustrated and described my invention in connection withone embodiment thereof, it is to be understood that I do not intend tobe limited to this embodiment or otherwise than by the spirit and scopeof the appended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In a vehicle brake system, in combination, a plurality of vehicleaxles, a brake means associated with each of said axles, means foreffecting an application of all of said brake means, a plurality ofelectrical devices each of which has a balanced and an unbalancedposition, means for maintaining all of said electrical devices in saidbalanced position so long as all of said axles are rotating atsubstantially the same speed,

means for unbalancing one or more of said electrical devices when one ormore of said axles reduce in speed below that of the other of saidaxles, and 'means operative when one or more of said electrical devicesare in unbalanced posiposition, means for maintaining all of said relaysin a balanced position so long as all of said axles are rotating atsubstantially the same speed, means operative when one or more of saidaxles reduce in speed below that of the other of said axles forunbalancing the relays associated with the axles which reduce in speed,and means rendered operative by the unbalanced relays for cutting oilthe supply to and releasing fluid under pressure from the brakecylinders associated with the axles which reduce in speed.

3. In a. vehicle brake system, in combination, brake means for producinga braking effect on the vehicle wheels, means for effecting anapplication oi the brake means, a plurality of electroresponsive deviceseach of which is associated with one or more vehicle wheels, each 01'said devices having a winding, means for forming a series circuitincluding the winding from each of said devices, contacts associatedwith each of said devices and closable when current is supplied to saidseries circuit, means for supplying current to said series circuit,means for preventing closing of said contacts so long as all of thevehicle wheels are rolling and operable to permit closing of thecontacts of the devices associated with sliding wheels, and meansresponsive to closing of said contacts for effecting a release of thebrake means associated with sliding wheels.

4. In a vehicle brake system, in combination, brake means for producinga braking effect on the vehicle wheels, means for effecting anapplication of the brake means, a plurality of relays each of which isassociated with one or more vehicle wheels, each of said relays havingnormally open contacts and a winding adapted when energized to closesaid contacts, means for forming a series circuit including the windingsfrom all of said relays, means for supplying current to said seriescircuit, means for preventing closing of the contacts of any of therelays when current is supplied to said series circuit so long as all01' the vehicle wheels are rolling at substantially the same speed,means operable to effect closing of the contacts of the relaysassociated with wheels which begin to slip, and means responsive to theclosing of the contacts of one or more of said relays for effecting arelease of the brake means on wheels associated with those relays.

5. In a vehicle brake system, in combination, brake means for producinga braking effect on the vehicle wheels, means for effecting anapplication of the brake means, a plurality of relays each of which isassociated with one or more vehicle wheels, each of said relays havingtwo windings and normally open contacts adapted to be closed when themagnetic force produced by energization of one of said windingsoverbalances the magnetic force produced by energization of the other ofsaid windings, means for forming an interconnected group including awinding from each of said relays, means for supplying current to thewindings in said interconnected group to a. degree sufilcient to closethe contacts of each relay, means for supplying current to the otherwindings of said relays to a degree sufllcient to prevent closing ofsaid contacts, means for causing the current supplied to any one or moreof said other windings to decrease sufiiciently to permit closing of thecontacts of the associated one or more relays when wheels associatedwith those relays begin to slide, and means responsive to closing of thecontacts of one or more of said relays for releasing the brake means onwheels associated with those relays.

6. In a vehicle brake system, in combination, a plurality oi brakecylinders, means for supplying fluid under pressure to all of said brakecylinders, an electroresponsive valve device associated with each ofsaid brake cylinders and operable when energized to cut off the supplyto and release of fluid under pressure from the associated brakecylinder, a plurality of relays each of which is adapted to controlenergization of one of said electroresponsive valve devices, each ofsaid relays having two windings oppositely wound, means for forming aseries circuit including a winding from each of said relays, meansassociated with all of the vehicle wheels for supplying current to saidseries circuit and to each relay winding not connected in said seriescircuit, means operable to decrease the current in the winding notconnected in said series circuit below that of the winding connected insaid series circuit of any one relay when the wheels associated withthat relay begin to slip, whereby that relay is operated to close itscontacts, and means responsive to closing of the contacts of' that relayfor energizing the electroresponsive device associated with the slippingwheels.

7. In a vehicle brake system, in combination, a plurality of rotatablemembers, a brake cylinder associated with each of said members, meansfor supplying fluid under pressure to all of said brake cylinders, aplurality of sources of current supply each of which is associated witha diil'erent one of said rotatable members, a plurality of relays eachof which has two windings and contacts adapted to be operated when theenergization of one winding is decreased a predetermined amount belowthe energization of the other winding, means for forming a seriescircuit including a winding from each of said relays and including allof said sources of current supply, means for connecting each of theother windings of said relays to a different one of said sources ofcurrent supply, means whereby when the current supplied by a sourcedecreases due to a decrease in rotation of the associated rotatablemember below the speed of rotation of the other rotatable members theenergization of the said other winding connected to said source isdecreased sufllciently to cause the one relay to operate its contacts,and means responsive to operation 01' the contacts of the one relay forcutting of]! the supply to and releasing fluid under pressure from theassociated brake cylinder.

8. In a vehicle brake system, in combination, a plurality of brakemeans, means for effecting an application of all of the brake means, aplurality of sources of current supply, a plurality of contacts, aplurality of windings adapted when energized to operate said contacts,means for connecting said windings and said sources in a series circuitto energize said windings, means responsive to current supplied by eachof said sources for preventing each of said windings individually fromoperating said contacts, means operable upon a decrease of currentsupplied by any one or more of said sources to cause one or more of saidwindings to operate contacts associated with said one or more windings,and means responsive to operation of said contacts for effecting arelease of one or more of said brake means.

9. In a vehicle brake system, in combination, a plurality of rotatablebraking elements, a genorator associated with each of said elements andadapted to produce a current when said element is rotating, a brakecylinder associated with each of said elements, means for supplyingfluid under pressure to all of said brake cylinders, a plurality ofrelays each of which has normally open contacts and two oppositely woundcoils, a plurality of rectifier devices each of which is connected to adifferent one of said generators, means for forming a series circuitincluding a winding from each of said relays and all of said rectifierdevices, means for connecting each of the other coils of said relays toa different one of said rectifier devices, and means rendered operablewhen the current produced by one of said generators decreases by apredetermined amount below the current produced by the other of saidgenerators for causing the associated relay to close its contacts, andmeans responsive to closing of said contacts for cutting off the supplyto and releasing fluid under pressure from the brake cylinder associatedwith said one generator.

10. In a vehicle brake system, in combination, a plurality of brakecylinders, means for supplying fluid under pressure to all of said brakecylinders, a generator associated with each of said brake cylinders andoperable to produce a current while the vehicle is in motion, aplurality of relays each of which has a first coil and a second coil,means for connecting all of the first coils in a series circuit, meansfor supplying current to said series circuit from all of saidgenerators, means for connecting the second coil of each relay in shuntwith the first coil of that relay, a valvular device connected in serieswith each of said second coils, contacts associated with each of saidrelays and adapted to be operated when the energization of said firstcoil exceeds by a predetermined amount the energization of said second,

coil, said valvular devices being effective to cause the first coil ofone relay to be energized greater than the second coil of that relay bysaid predetermined amount upon a decrease in current supplied by one ofsaid generators, and means controlled by said contacts for controllingthe supply of fluid under pressure to and its release from said brakecylinders.

11. In a vehicle brake system, in combination, two brake cylinders,means for supplying fluid under pressure to the two brake cylinders, tworelays each of which has two windings oppositely wound and contactsadapted to be operated when energization of one winding exceedsenergization of the other winding by a predetermined amount, means forforming a series circuit including a winding from each of said relays,means for supplying current to said series circuit and to each of theother windings of said relays, means operable upon a sliding of avehicle wheel for decreasing the current in one of the windings notconnected in said series circuit, whereby the relay associated with thatwinding is caused to operate its contacts, and means responsive tooperation of the contacts of that relay for cutting 011 the supply toand releasing fluid under pressure from one brake cylinder.

12. In a vehicle brake system, in combination, two rotatable brakemembers, a generator and a brake cylinder associated with each of saidbrake members, means for supplying fluid under pressure to both of saidbrake cylinders, two relays each of which has two windings and contactsadapted to be operated when energization of due of said windings exceedsenergization of the other of said windings by a predetermined amount,means for forming a series circuit including a winding of each of saidrelays, means for supplying current to said series circuit from both ofsaid generators, means for connecting the other winding of each relay inshunt with the first mentioned winding of that relay, means operableupon a decrease in current supplied by one of said generators fordecreasing the current in one of the second mentioned windings of one ofsaid relays whereby that relay is caused to close its contacts, andmeans rendered. operable upon.

closing of said contacts for cutting ofi the supply to and releasingfluid under pressure from one of said brake cylinders.

13. In a vehicle brake system, in combination, a plurality of rotatablebraking elements, an alternating current generator associated with eachof said elements and adapted to produce an al-' ternating current whensaid element is rotating, a brake cylinder associated with each of saidelements, means for supplying fluid under pressure to all of said brakecylinders, a plurality of relays each of which has normally opencontacts and two oppositely wound coils, a plurality of rectifierdevices for changing the alternating current to direct current each ofwhich is connected to a diiferent one of said generators, means forforming a series circuit including a winding from each of said relaysand all of said rectifier devices, means for connecting each of theother coils of said relays to a different one of said rectifier devices,and means rendered operable when the current produced by one of saidgenerators decreases by a predetermined amount below the currentproduced by the other of said generators for causing the associatedrelay to close its contacts, and means responsive to closing of saidcontacts for cutting ofi the supply to and releasing fluid underpressure from the brake cylinder associated with said one generator.

14. In a brake equipment for vehicles, in combination, a plurality ofbrake cylinders one associated with each vehicle wheel axle, meansforsupplying fluid under pressure to said brake cylinders to apply thebrakes, electrical means associated with each of the several vehiclewheel axles, and means responsive to a differential relation betweensaid electrical means set up when the wheels associated with one axleslide for effecting the release of fluid under pressure from the brakecylinder associated with the sliding wheels.

15. In a brake equipment for vehicles, in combination, a plurality ofbrake cylinders associated with separate vehicle wheel axles, means forsupplying fluid under pressure to said brake cylinders to apply thebrakes, electrical means associated with each of the several vehiclewheel axles for controlling an electric quantity in accordance withvariations in the speed of its associated vehicle wheels, and meansresponsive to a difierential relation between said electrical quantitiesset up when one axle is revolving at a slower rate of speed than theother axle for eflecting the release of fluid under pressure from abrake cylinder associated withthe vehicle wheel axle that is revolvingat the slower rate of speed.

16. In a brake equipment for vehicles, in combination, a plurality ofpairs of car wheels, braking means associated with each 01' said pairsof wheels, electrical means operable while the brakes are applied, anddifferentially responsive to a variation in the speed of rotationbetween said pairs of car wheels for reducing the degree of applicationof the brakes on a pair of wheels that operate at a slower rate of speedthan other pairs of wheels.

1'7. In a brake equipment for vehicles, in combination, a plurality ofpairs of car wheels, braking means associated with each of said pairs ofwheels, electrical means associated with each pair 01' car wheels fordelivering an output voltage that is a measure of the speed of thewheels, common means connecting said several electrical means, andelectrical means responsive to a variation in the speed of rotationbetween said pairs of car wheels for efiecting a reduction in the degreeof application of the brakes on a pair of wheels that operate at aslower rate of speed than other pairs of wheels.

18. In a brake equipment for vehicles, in combination, a plurality ofgroups of vehicle wheels, a brake cylinder associated with each wheelgroup, an electrical means associated with each wheel group andresponsive to the speed thereof, and means responsive to a reduction inthe speed of the wheels of one group with respect to the speed of thewheels of other groups and controlled by said electrical means foreffecting the release of fluid under pressure from the brake cylinderassociated with said first named wheel group.

19. In a. brake equipment for vehicles, in combination, a plurality ofpairs of vehicle wheel groups, a brake cylinder associated with eachpair of wheels, a brake valve for controlling the supply of fluid underpressure to said brake cylinders to apply the brakes, an electricgenerator associated with each pair of wheels and operated in accordancewith the speed thereof, a common circuit connecting said severalgenerators, relay means responsive to a reduction in the speed of one ofsaid generators with respect to the speed of other of said generatorsfor controlling the release of fluid under pressure from its associatedbrake cylinder independently of the operation of said-brake valve.

20. In a brake equipment for vehicles, in combination, braking means,manually operable means for controlling the application and release ofthe brakes, electrically operable means for decreasing the degree ofapplication of the brakes independently of said manually operable means,and control means therefor comprising contact means differentiallyresponsive to the speeds of the vehicle wheels.

21. In a brake equipment for vehicles, in combination, a brake cylinder,manually operable means for controlling the suply of fluid underpressure to and from said brake cylinder, electrical means operable torelease fluid under pressure from said brake cylinder independently ofsaid manually operable means, a source of electric energy, and meansresponsive to a fixed difierential between the speed of the vehicle andthe speed of the vehicle wheel for operatively relating said electricalmeans and said source.

JOHN W. LOGAN, JR.

